Method for Managing Keys and/or Rights Objects

Abstract

One or more rights objects (RO) files may be used for storing RO's preferably in the protected area available only to authenticated users. A RO navigation file is stored preferably in an unprotected public area containing status bits, where each status bit identifies whether a location in a RO file contains a valid RO or not. Preferably, there is a one-to-one correspondence between the location for a RO in a RO file and a location in the RO navigation file for the status bit which identifies whether its corresponding location in the RO file contains a valid RO or not. Whether a particular location in a RO file contains a valid RO or not can be found by checking its corresponding status bit in the RO navigation file. By finding out whether a particular location in a RO file contains a valid RO or not in this manner, it is possible to delete ROs without having to go through an authentication process. The process of finding an empty slot in the RO file for storing a new RO is also simplified. This greatly increases the efficiency of RO management. A similar system may be used for management of content encryption / encryption keys for protecting content files.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a divisional of U.S. patent application Ser. No. 11 / 283,221, which is hereby incorporated by references. Also, this application is related to U.S. patent application Ser. No. 11 / 283,225.BACKGROUND OF THE INVENTION[0002]This invention relates in general to encryption / decryption systems, and in particular a system for managing keys used for encryption and / or decryption and / or rights objects that control use of or access to content.[0003]Media content such as music, video and games is distributed increasingly as digital files. Such digital content has been distributed widely through a number of channels, including the internet and the use of storage devices. The digital content may be stored in a number of different types of devices, such as magnetic or optical disks, tapes, and non-volatile memories such as flash memories. The digital content in these storage devices can be played, stored and operated by a wide variety o...

AI Technical Summary

Benefits of technology

[0008]According to one embodiment of the invention, a key navigation file and one or more key storage files may be used to facilitate key management. The content files that are to be encrypted and / or decrypted each comprises a header portion containing location information which indicates which key storage file contains the key that is to be used for encrypting and / or decrypting the content file. The key navigation file contains status information that indicates whether a valid key is stored at one or more locations in the one or more key storage files. This facilitates a process of locating a location in the one or more key storage files for storing a key. Preferably the status information indicates one or more locations in the one or more key storage files at which one or more valid key(s) are not stored.

[0010]In one implementation of the above embodiment, the key navigation file is stored in the public unprotected area of a storage medium and the one or more key storage files for storing the keys are stored in a protected area of the medium which can be accessed only by authenticated users, applications or devices. For obvious reasons, it is desirable to store the one or more key storage files in the protected area not accessible to unauthorized access. Thus, by providing the key navigation file in the public area which contains status information indicating whether one or more locations in the key storage file(s) contains a valid key or not, this greatly enhances key management performance. Thus, one does not need to access the protected area in order to find out whether a particular key in the key storage file is valid or not; instead, this information is readily available in the key navigation file which can be accessed without authentication. This feature also makes it particularly easy to delete a content file and its encryption / decryption key. The deletion of the key can simply be accomplished in one implementation by changing the status information in the key navigation file, without actually having to access the key storage file in the protected area containing the key in order to delete the key.

[0024]Thus, according to yet another embodiment of the invention, a rights object navigation file and one or more rights object storage files may be used to facilitate rights object management. The content files that are to be controlled by means of the rights objects each comprises a header portion containing location information which indicates which rights object storage file contains the rights object that is to be used for controlling use of and / or access to the content file. The rights object navigation file contains status information that indicates whether a valid rights object is stored at one or more locations in the one or more rights object storage files. This facilitates a process of locating a location in the one or more rights object storage files for storing a rights object key. Preferably the status information indicates one or more locations in the one or more rights object storage files at which one or more valid key(s) are not stored.

[0026]In one implementation of the above embodiment, the rights object navigation file is stored in the public unprotected area of a storage medium and the one or more rights object storage files for storing the rights objects are stored in a protected area of the medium which can be accessed only by authenticated users, applications or devices. For obvious reasons, it is desirable to store the one or more rights object storage files in the protected area not accessible to unauthorized access. Thus, by providing the rights object navigation file in the public area which contains status information indicating whether one or more locations in the rights object storage file(s) contains a valid rights object or not, this greatly enhances rights object management performance. Thus, one does not need to access the protected area in order to find out whether a particular rights object in the rights object storage file is valid or not; instead, this information is readily available in the rights object navigation file which can be accessed without authentication. This feature also makes it particularly easy to delete a content file and its associated rights object. The deletion of the rights object can simply be accomplished in one implementation by changing the status information in the rights object navigation file, without actually having to access the rights object storage file in the protected area containing the rights object in order to delete the rights object.

Problems solved by technology

Therefore, a problem that can be anticipated in digital rights management (“DRM”) is the capability to efficiently manage a large number of keys and to determine the right key for encrypting and / or decrypting any particular digital file.

While the above key management systems may be useful for some applications, they each have their limitations.

None of the above systems are entirely satisfactory.

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